Field of the Invention
This invention relates to medical imaging systems. More particularly, this invention relates to improvements in medical image analysis.
Description of the Related Art
Three-dimensional (3-D) images of internal organs are useful in many catheter-based diagnostic and therapeutic applications, and real-time imaging is widely used during surgical procedures. Ultrasound imaging is a relatively convenient mode of real-time imaging, though the resolution of real-time ultrasound images is generally not as good as the resolution obtained from other imaging modalities, such as computerized tomography (CT) and magnetic resonance 20 imaging (MRI).
Methods for 3-D mapping of a heart using a position-sensing catheter are well known in the art. For example, U.S. Pat. No. 5,738,096 to Ben-Haim, whose disclosure is incorporated herein by reference, describes a position-sensing probe brought into contact with multiple points in the body to generate an anatomical map. Physiological properties, including electrical activity on the surface of the heart, may also be acquired by the catheter.
Commonly assigned U.S. Pat. No. 8,320,711 to Altmann et al., which is herein incorporated by reference, discloses creating an anatomical map by delineation of a 3-D image of the cavity based. The method involves automated segmentation of a 3-D image along a 3-D segmentation contour and enhancement of a 3-D map based on the segmentation contour.
A body-surface mapping technique for mapping the heart is disclosed in commonly assigned U.S. Patent Application Publication No. 2008/0058657 by Schwartz et al., which is herein incorporated by reference. A reliable endocardial map is obtained by constructing a matrix relationship between a small number of endocardial points and a large number of external receiving points using a multi-electrode chest panel. Inversion of the matrix yields information allowing the endocardial map to be constructed.
Another disclosure describing a body-surface method for mapping the heart is U.S. Patent Application Publication No. 2012/0035459 by Revishvili et al. On a set of surface electrocardiograms for each discrete moment of the cardiocycle, values of the heart electric field potential at points of ECG-recording are determined, and a value of the electric field potential at each point of the chest surface is calculated by interpolation. Based on data of any visualization methodology, boundaries of chest and lungs surfaces and of the heart epicardial surface are determined.
Registration of electroanatomical maps with anatomical landmarks produced by other modalities is known, for example, from U.S. Patent Application Publication No. 2007/0049817, and commonly assigned U.S. Pat. No. 7,517,318 to Altmann et al., which are herein incorporated by reference. The latter document discloses a technique of image registration comprising providing a pre-acquired image of the target and placing a catheter having a position sensor, an ultrasonic imaging sensor and an electrode, in the patient's body. Positional information of a portion of the catheter in the patient's body is determined using the position sensor and electrical activity data-points of a surface of the target are acquired using the electrode. An ultrasonic image of the target is obtained using the ultrasonic imaging sensor and positional information for the electrical activity data-points of the surface of the target is determined. An electrophysiological map of the target is generated based on the electrical activity data-points and the positional information for the electrical activity data-points. Positional information for any pixel of the ultrasonic image of the target is determined. The pre-acquired image and the electrophysiological map are registered with the ultrasonic image and the result displayed.
Using the methods disclosed in the above-noted U.S. Patent Application Publication No. 2007/0049817 and U.S. Pat. No. 7,517,318, features such as scar tissue in the heart, which typically exhibits lower voltage than healthy tissue in the electro-anatomical map, can be localized and accurately delineated on the three-dimensional image.